netdev - Re: [PATCH v2 2/3] sctp_diag: export timer value only if it is active

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Date:	Wed, 3 Aug 2016 18:51:15 -0300
From:	Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:	Phil Sutter <phil@....cc>
Cc:	David Miller <davem@...emloft.net>,
	Xin Long <lucien.xin@...il.com>, netdev@...r.kernel.org
Subject: Re: [PATCH v2 2/3] sctp_diag: export timer value only if it is active

On Wed, Aug 03, 2016 at 11:23:12PM +0200, Phil Sutter wrote:
> Since it is exported as unsigned value, userspace has no way detecting
> whether it is negative or just very large. Therefore do this in kernel
> space where it is a simple comparison.
> 
> Signed-off-by: Phil Sutter <phil@....cc>
> ---
> Changes since v1:
> - Introduce local variable to shorten long lines.
> - Use timer_pending() to decide whether to export the timer value.
> - Export the primary path's value instead of garbage.

This is now the most important change on the patch IMO. Can we mention
it on changelog itself?

A Fixes tag is welcomed too, as previous values were incorrect.

> - If not exporting, zero fields to not confuse userspace.
> ---
>  net/sctp/sctp_diag.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/net/sctp/sctp_diag.c b/net/sctp/sctp_diag.c
> index f69edcf219e51..f728ef04a7b2d 100644
> --- a/net/sctp/sctp_diag.c
> +++ b/net/sctp/sctp_diag.c
> @@ -13,6 +13,7 @@ static void inet_diag_msg_sctpasoc_fill(struct inet_diag_msg *r,
>  {
>  	union sctp_addr laddr, paddr;
>  	struct dst_entry *dst;
> +	struct timer_list *t3_rtx = &asoc->peer.primary_path->T3_rtx_timer;
>  
>  	laddr = list_entry(asoc->base.bind_addr.address_list.next,
>  			   struct sctp_sockaddr_entry, list)->a;
> @@ -40,10 +41,15 @@ static void inet_diag_msg_sctpasoc_fill(struct inet_diag_msg *r,
>  	}
>  
>  	r->idiag_state = asoc->state;
> -	r->idiag_timer = SCTP_EVENT_TIMEOUT_T3_RTX;
> -	r->idiag_retrans = asoc->rtx_data_chunks;
> -	r->idiag_expires = jiffies_to_msecs(
> -		asoc->timeouts[SCTP_EVENT_TIMEOUT_T3_RTX] - jiffies);
> +	if (timer_pending(t3_rtx)) {
> +		r->idiag_timer = SCTP_EVENT_TIMEOUT_T3_RTX;
> +		r->idiag_retrans = asoc->rtx_data_chunks;
> +		r->idiag_expires = jiffies_to_msecs(t3_rtx->expires - jiffies);
> +	} else {
> +		r->idiag_timer = 0;
> +		r->idiag_retrans = 0;
> +		r->idiag_expires = 0;
> +	}
>  }
>  
>  static int inet_diag_msg_sctpladdrs_fill(struct sk_buff *skb,
> -- 
> 2.8.2
>